Wide band siren system

ABSTRACT

A WIDE BAND NOISE SOURCE HAVING FOUR SIREN ROTOR BLADES POSITIONED IN CLOSE PROXIMITY TO EACH OTHER AND SUPPORTED WITHIN TWO RING SUPPORT MEMBERS WHICH ARE SECURED TO A BASE SUPPORT MEMBER. THE TWO OUTER ROTOR BLADES ARE EACH SUPPORTED ON JOURNAL MEMBERS IN TWO BEARINGS IN THE RING SUPPORT MEMBERS. THE TWO CENTER ROTOR BLADES ARE SUPPORTED ON SHAFT JOURNAL MEMBERS IN FOUR BEARING SUPPORTED WITHIN THE JOURNAL MEMBERS FOR THE TWO OUTER ROTOR MEMBERS. THE JOURNAL MEMBERS FOR THE FOUR ROTORS HAVE PULLEYS KEYED TO THEM SO THAT THE FOUR ROTORS CAN BE DRIVEN THROUGH V-BELTS BY FOUR ELECTRIC MOTORS. LABYRINTH SEALS ARE PROVIDED TO KEEP DUST PARTICLES AND DIRT AWAY FROM THE BEARINGS.

March 1971 H. F. WOLFE 3,572,285

WIDE BAND SIREN SYSTEM Filed Nov. 5, 1969 5 Sheets-Sheet 1 March 23,1971 H. F. WOLFE 3,572,285

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WIDE BAND SIREN SYSTEM Filed Nov. 5, 1969 5 Sheets-Sheet IN VENTORHOWflfD A". W01 FA March 23, 1971 H. F. WOLFE 3,572,285

WIDE BAND SIREN SYSTEM Filed Nov. 5, 1969 5 Sheets-Sheet 4 E-L- j[NV/INTO R. fl n/co F- w B)" 7%? arr-0e (y March 23, 1971 H. F. WOLFE3,572,285

WIDE BAND SIREN SYSTEM Filed Nov. 5, 1969 5 Sheets-Sheet 5 BY W UnitedStates Patent Office 3,572,285 WIDE BAND SIREN SYSTEM Howard F. Wolfe,Kettering, Ohio, assignor to the United States of America as representedby the Secretary of the Air Force Filed Nov. 5, 1969, Ser. No. 874,167Int. Cl. G01k 7/00 US. Cl. 116-147 3 Claims ABSTRACT OF THE DISCLOSURE Awide band noise source having four siren rotor blades positioned inclose proximity to each other and supported within two ring supportmembers which are secured to a base support member. The two outer rotorblades are each supported on journal members in two hearings in the ringsupport members. The two center rotor blades are supported on shaftjournal members in four bearings supported within the journal membersfor the two outer rotor members. The journal members for the four rotorshave pulleys keyed to them so that the four rotors can be driven throughV-belts by four electric motors. Labyrinth seals are provided to keepdust particles and dirt away from the bearings.

BACKGROUND OF THE INVENTION Various types of sirens have been developedfor the generation of high intensity wide band noise. One such device isshown in FIGS. 6 and 6a of the patent to Cole et al. 3,072,094. Certainproblems exist in devices of this type due to the high radial and axialloads on the bearings due to bending stress induced in the rotor due tofluctuation of the air pressure load on the rotor blades.

A device of the type shown in the patent to Cole et al. is shown anddescribed in Technical Report AFFDL-TR- 66-8, March 1966 Design and'Performance of 15 Kw. Wide 'Band Acoustic Facility," available fromDefense Documentation Center, No. AD 634,904. As pointed out on page 4of the technical report, rotor speeds vary between 625 r.p.m. and 5,000r.p.m. As can be seen from the fourth paragraph, on page 4, whenadjacent rotors are counter rotated the relative speed on the bearingsbetween the rotors is the sum of speeds of the rotors or at 5,000 r.p.m.rotor speed, the speed seen by the bearings between the rotors is 10,000r.p.m. For the large bearings used the suggested maximum speed for longlife of the bearings is 6,300 r.p.m. Thus an increase over this speed,such as when the relative speed is 10,000 r.p.m., will shorten the lifeof the bearings.

SUMMARY OF THE INVENTION According to this invention external support isprovided instead of supporting the rotors on a central shaft as in thedevice of the report. Thus the larger bearing between the support andthe outer rotor sees only the relative speed between the outer rotorjournal and the stationary support and the bearings which experience thelarger relative rotation between the two rotor shafts have a smallerdiameter and therefore can withstand greater relative speeds.

IN THE DRAWINGS FIG. 1 is a partially schematic end view of the rotorassembly for a wide band noise source according to the invention;

FIG. 2 is a reduced schematic top view of the device of FIG. 1;

FIG. 3 is a partially cutaway side view of the rotor unit for the deviceof FIGS. 1 and 2;

FIG. 4 is an end view of one of the rotor elements of the device of FIG.1;

FIG. 5 is an end view of a second rotor element of the device of FIG. 1;

3,572,285 Patented Mar. 23, 1971 DESCRIPTION OF THE INVENTION Referenceis now made to FIGS. 1 and 2 of the drawings which show a wide bandnoise generator 10 having four rotors shown schematically at 12, 13, 14,and 15. The rotors 12 and 13 are supported by a ring support housingmember 16 and the rotors 14 and 15 are supported by ring support housingmember 18, as will be described later. The housing 16 is supported on asupport frame shown generally at 20 by means of flanges 21 and 22. Thehousing 18 is supported on support frame 20 by means of flanges 23 and24. Air is supplied to the rotors by means of five air passages shownschematically at 19".

The rotor 12, having blades 12 as shown in FIG. 7, is supported withinthe housing 16 by means of a hollow journal member 25 which runs inbearings 27 and 28. Spacers 29 are positioned between bearings 27 and28. The journal member 25 is secured to the rotor 12 by means of bolts30, one of which is shown in FIG. 3.

The rotor 13, having blades 13 as shown in FIG. 6, is supported withinjournal member 25 by means of a shaft journal member 32, which is keyedto the rotor, and four bearings 34, 35, 36, and 37. A spacer 38 islocated between bearings 35 and 36.

Rotor 12 is driven by means of a pulley member 40 which is keyed to thejournal member 25, and the rotor 13 is driven by a pulley member 42which is keyed to shaft 32.

The rotor 15, having blades 15 as shown in FIG. 4, is supported withinhousing 18 by means of hollow journal member 47 secured to the motor bymeans of bolts 49, one of which is shown, and two bearings 50, one ofwhich is shown. The rotor 14, having blades 14' as shown in FIG. 5, issupported within the journal member 47 by means of a shaft journalmember 52 keyed to the rotor 14 and four bearings 53, two of which areshown. Rotor 15 is driven by a pulley 57 keyed to journal member 47 androtor 14 is driven by a pulley 55 keyed to shaft 52. As shown in FIG. 8,the rotors 12, 13, 14, and 15 are driven by individual electric motors60, 61, 62, and 63, respectively, through V-belts which engage pulleys40, 42, 55, and 57. The rotors 12, 13, 14, and 15 are all dynamicallybalanced to within .01 ounce inch at 5,000 r.p.m.

Labyrinth seals 43, 44, and 45 keep dust and other foreign matter fromreaching the bearings 27, 28, 34, 35, 36, and 37.

In the operation of the device, the rotors are driven by electric motors60, 61, 62, and 63 in the same manner as in the technical reportreferenced above. The rotors 12 and 14 are driven in one direction andthe rotors 13 and 15 are driven in the opposite diection. Air, from airsupply 58, is supplied to the rotors through passages 19, shownschematically at 19' in FIG. 1, in about the same manner as in thereferenced technical report except that five passages 19 are describedwhereas only four passages are dc scribed in the report. However, thenumber of passages amounts to a matter of design. The small hornsections 64 feed a large horn section 65 as in the reference technicalreport. The direction of air flow in FIG. 3 is shown by the arrow 59.The speed of the individual electric motors need not be the same and maybe varied through a range of speeds for some applications.

There is thus provided a wide band noise source which is more rugged andwhich produces longer bearing life than prior art devices.

I claim:

1. A wide band noise source comprising a base support member; a firstring support member secured to said base support member; a second ringsupport member secured to said base support member in predeterminedfixed spaced relation to said first ring support member; a first rotormember having a plurality of blades positioned in a predeterminedangular relation around the periphery thereof; means for rotatablysupporting said first rotor within said first ring support member; asecond rotor member having a plurality of blades positioned in apredetermined angular relation around the periphery thereof; means forrotatably supporting the second rotor member Within the support meansfor said first rotor member; a third rotor member having a plurality ofblades positioned in a predetermined angular relation around theperiphery thereof; means for rotatably supporting the third rotor memberwithin said second ring support member; a fourth rotor member having aplurality of blades positioned in predetermined angular relation aroundthe periphery thereof; means for rotatably supporting the fourth rotormember within the support means for said third rotor member; said first,second, third, and fourth rotor members being positioned in closeproximity to each other; means for driving the first and third of saidrotor members at predetermined speeds in one direction; means fordriving the second and fourth of said rotor members at predeterminedspeeds in the opposite direction; means for directing at least one highvelocity air stream through the blades of said rotors.

2. The device as recited in claim 1 wherein said means for supportingsaid first and third rotor members within said first and second ringsupport members are hollow shaft journals secured to the first and thirdrotors and mounted in bearings Within the ring support members and themeans for supporting the second and fourth rotors are shaft journalssecured to the second and fourth rotors and mounted in bearings Withinsaid hollow shaft journals.

3. The device as recited in claim 2 wherein the relative angularposition of the blades on said rotors is different on each of the rotorsand wherein air is directed through the rotors at a plurality of spacedpositions around the rotors.

References Cited UNITED STATES PATENTS 2,222,322 11/1940 Schmacke340-405 2,912,958 11/1959 Von Gierke et a1. 116147 3,072,094 1/1963 Coleet a1 116-147 OTHER REFERENCES Publication: Technical ReportAFFDL-TR-668, March 1966, Design and Performance of 15 Kw., Wide BandAcoustic Facility, Defense Documentation Center, No. AD 634,904.

LOUIS J. CAPOZI, Primary Examiner US. Cl. X.R.

